15的英文怎么拼

　　You must return the book in fifteen days.

　　你必須在十五天內歸還書籍。

　　I have fourteen roosters and fifteen hens.

　　我有十四只公雞和十五只母雞。

　　There are fifteen boys and nineteen girls.

　　男生有十五位，女生有十九位。